When Barack Obama took office in 2008, one of the most difficult things for conservatives was the fact that he soon had a compliant and Democrat-controlled Congress to do his bidding. With the
defection of Arlen Specter in April of 2009 and the seating of Al Franken as a result of the disputed Minnesota senatorial race, the Republicans lacked even the 41 votes necessary to stop the Democrats in the Senate, although they finally gained exactly that number with the surprise election of Scott Brown of Massachusetts.
However, after that point, the Republicans in Congress
were able to stop some of the Obama agenda after gaining the ability to muster at least 41 votes in the Senate, and after they gained the House in 2010. That's why the Democrats in the Senate
triggered the nuclear option for judicial appointments in November of 2013, when they still controlled both the presidency and the Senate but the Republicans had gained enough senators to block judicial confirmation under the old (non-nuclear) rules. But under the new nuclear option rules (see
this for a full explanation of how it works), a simple majority of Democrats could successfully force a vote to confirm Obama's judicial appointments, rather than needing to gain 60 votes to close down debate.